Atherosclerotic aortic arch debris has been implicated as risk factor for ischemic stroke. Stroke associated with arch debris afflicts approximately 90,000 Americans annually, but it has not been established whether arch debris is an independent mechanism of focal cerebral ischemia warranting specific investigation and treatment or simply a marker for generalized atherosclerosis. This large population-based case-control and cohort study will use the resources of the Rochester Epidemiology Project and May Echocardiography Laboratory to: 1) Determine whether arch debris is a risk factor more closely related to a causal mechanism of first focal cerebral ischemia (TIA, ischemic stroke, cryptogenic stroke) independent of generalized atherosclerosis; and 2) Determine the rates of subsequent stoke occurrence among individuals with first focal cerebral ischemia who have arch debris compared to the rates for individuals with first focal cerebral ischemia who have no arch debris. Cases and cohort members are 570 residents with a biplane for multiplane transesophageal echocardiogram (TEE) performed to evaluate a first ischemic stroke or TIA from 1993-99. The multiple logistic models of the case control study analyses will be repeated with and without controlling for generalized atherosclerosis and using two different types of controls without stroke or TIA: 1) 1300 residents with a biplane or multiplane TEE performed for clinical indications other than stroke or TIA; 2) 560 randomly selected residents who had a biplane or multiplane TEE for the SPARC study. The ratio of the odds of first focal cerebral ischemia for those with arch debris to the odds for those without arch debris derived with and without controlling for generalized atherosclerosis and using the two different types of controls will be compared. The study will therefore not only determine whether arch debris is a risk factor for first focal cerebral ischemia independent of atherosclerosis in general, but will also test different approaches to the design of population-based case-control studies. The cohort study of individuals with first focal cerebral ischemia will compare the Kaplan-Meier estimates of survival free of subsequent stroke for those who have arch debris to those who do not, and th proportional hazards model will determine whether arch debris is an independent determinant of subsequent stroke adjusting for confounding variables, including generalized atherosclerosis. This study will determine whether clinical trials of specific treatments aimed at primary and secondary stroke prevention among individuals with arch debris are warranted, and if so, assist in their design.